Parallel inclined plate separators have been used in the past to separate immiscible liquids of different specific gravities, as for example, separating oil from water. As the water, containing oil and suspended solids, enters the separating vessel, the larger oil droplets will separate out from the water and rise to the top of the vessel, while the larger suspended solids will settle to the bottom of the vessel. After this initial separation phase, the water then flows through the inclined parallel plates and the shorter rise distance provided by the parallel plates permits small oil droplets to separate out from the water and collect on the surface of the plates. The angle of the parallel plates and the flow of the water permits the oil droplets to flow upwardly along the plates to the top of the vessel for collection.
In the past, the separating vessels utilizing inclined plates have usually been rectangular in configuration with open tops and it has been the practice to collect the oil in a separate oil collection zone at the top of the vessel, and the collected oil is overflowed through a weir to a collection container.
It has also been common practice in the past to pre-assemble the inclined separator plates as an assembly or pack, so that the entire pack can be removed from the separating vessel for routine maintenance or repair.
Although cylindrical vessels are generally cheaper to fabricate than rectangular units, cylindrical units have not been generally used in the past. This is primarily due to the increased complexity of a separator plate pack designed for a cylindrical vessel and the difficulty associated with oil collection and sensor operation for horizontal vessels. Horizontal vessels are desirable from a separation standpoint but problems arise in separation and removal of the oil layer in horizontally mounted vessels used in marine applications due to yawing and rolling of the ship.